The Prevalence and Anatomical Patterns of Intramuscular Coronary Arteries. A Coronary Computed Tomography Angiographic Study

Objectives: This study sought to report prevalence and radiologic patterns of intramuscular coronary arteries (myocardial bridging) on coronary computed tomographic angiography (CCTA). Background: Reported prevalence of intramuscular coronary arteries varies between 5% and 86% in autopsy and 0.8% and 4.9% in coronary angiography. Intramuscular coronary arteries can cause technical problems during coronary bypass surgery, including inadvertent perforation of the right ventricle. Methods: One hundred and eighteen consecutive patients were studied with CCTA using Brilliance 40/64 multidetector computed tomography (Philips Medical Systems, Cleveland, Ohio). Parameters evaluated were number, length, and depth of intramuscular coronary segments; diameter and evidence of atherosclerosis in the involved artery proximal and within the intramuscular segment; and its course in relation to the interventricular septum and right ventricular wall. Results: Forty-seven intramuscular segments were identified in 36 of 118 (30.5%) patients. Most were located in mid left anterior descending coronary artery (LAD), 27 of 47 (57%), and distal LAD, 7 of 47 (15%). The CCTA features in the LAD showed 3 patterns: superficial septal, 10 of 34 (29.4%); deep septal, 14 of 34 (41.1%); and right ventricular type, 10 of 34 (29.4%). Intramuscular segment length ranged from 13 to 40 mm. Coronary diameter proximal and within the affected segment was 2.2 ± 0.5 mm versus 1.6 ± 0.6 mm for the LAD, and 1.9 ± 0.3 mm versus 1.5 ± 0.6 mm for the remaining arteries, respectively. Depth ranged from 0.1 to 5.6 mm. Conclusions: Prevalence of intramuscular coronary arteries on CCTA is in concordance with most pathological reports and higher than in angiographic series. The CCTA clearly showed presence, course, and anatomical features of intramuscular coronary arteries. Coronary computed tomographic angiography may provide potentially useful information in the preoperative evaluation of candidates for coronary bypass surgery.